When the steel blade of a circular saw rotates at high speeds it generates a disturbing sound. As saw blades to-day operate at speeds of between 60 and 90 meters per second and the tendency is to accelerate the speed even further, which seems possible in view of the increasingly improved constructions and materials, the need for noise-suppressed saw blades becomes more and more pronounced.
Several ways of solving this problem have been suggested. On the market exists for instance so-called sandwich saw blades consisting of two core discs put together, with a layer of paper (cellulose) or other suitable noise-suppressing material between them, these discs being welded at their peripheries to a toothed rim of hard metal. One disadvantage with this type of circular saw blades is that after a period of operational life with the saw blade working on tree trunks and similar materials, the noise-reducing material will gasify on account of the extremely high temperatures that occur locally on the blade, or else deteriorate in some other way, whereby the noise-reducing effect of the material is lost. Another suggested improvement is the boring of holes through the blade, whereafter the holes are filled with copper plugs. The noise-reducing effect is, however, comparatively small. In accordance with a third suggestion, noise-reducing screens are attached to the sawing machine proper at either side of the saw blade below the saw table, whereby the lower portion of the blade will rotate between the screens. One disadvantage of this arrangement is that when the saw blade is removed from its shaft or spindle, for instance when the saw teeth are to be reground, it is necessary to dismantle at least one of the two noise-reducing screens, usually the outer one.